The invention relates to a printing device, comprising several printing stations disposed one after the other in the lengthwise direction, and each comprising a main printing unit, at least one additional printing unit, drive means for driving the printing units, and conveyor means for conveying the material to be printed through the printing device.
Such a printing device is known. In such a printing device the additional printing unit is used to carry out an additional printing operation on the material to be printed, for example printing an additional colour, or carrying out a different type of printing operation. In the case of the known printing devices there are generally two different systems for placing the additional printing unit in the printing device. In the first system, a main printing unit in a conventional printing press is replaced by an additional printing unit in the form of a rotary screen printing device. When the main printing unit is replaced by the additional printing unit, the main printing unit selected is first detached at the appropriate drive point of the device and then removed therefrom, after which the new, additional printing unit is placed in this position in the device and connected to the drive of the main printing units. In the second system, an additional printing unit is added to the printing device. At a desired position, the printing stations are detached from each other and pushed apart. The additional printing unit is disposed in the space thus created, and is installed in the device and connected to the drive of the main printing units in the printing stations.
Although these printing devices have some flexibility as regards the position of the additional printing unit in the printing device, long fitting times are necessary for installing and converting the printing device, in view of the complexity of the operations which have to be carried out. Besides, in the case of the printing device described above, in which a main printing unit is replaced by the additional printing unit, the total number of printing operations is not increased. In the case of the printing device in which the additional printing unit is disposed between the main printing units, it is necessary for a part of the printing device to be movable and for the space required therefor to be present. This calls for additional facilities, with the costs which this involves.
The object of the invention is to provide a printing device in which the main printing units in the printing stations do not have to be removed or moved in order to add an additional printing unit, so that changeover and resetting times are short.